Disclosures about fair value of assets and liabilities (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Realized gains and losses included in net income for the periods in the condensed consolidated statements of income
Included in net income			$ (408)	$ 280
Hedged loans [Member]
Realized gains and losses included in net income for the periods in the condensed consolidated statements of income
Included in net income	(1,444)	298	(1,846)	224	(74)
Fair value interest rate swap agreements [Member]
Realized gains and losses included in net income for the periods in the condensed consolidated statements of income
Included in net income	1,444	(298)	1,846	(224)
Derivative loan commitments [Member]
Realized gains and losses included in net income for the periods in the condensed consolidated statements of income
Included in net income	(396)	503	(408)	280
Non Interest Income [Member]
Realized gains and losses included in net income for the periods in the condensed consolidated statements of income
Included in net income	$ (396)	$ 503